I am proposing to study the mechanical events in joint capsule which are related to the production of discharges in neuronal receptors located in the capsule. Isolated sections of capsule from the cat knee joint are studied in an apparatus where they can be subjected to known states of stress or strain. The section of capsule which is studied is approximately 10 x 10 mm in size. Stresses are estimated by measuring loads and boundary conditions. Strains are estimated by decorating the capsule surface with markers and following marker displacements which are observed with tissue loading. Neuronal discharges are recorded from single afferents innervating the isolated tissue, and related to components of stress or strain. To date, adequate strain measurements have not been made, but methods for doing so are being developed. Concurrent studies are being undertaken to examine the rheological properties of the joint capsule. Stress-strain-time studies are being done using uniaxial and biaxial loading configurations.